EATONVILLE, Wash. - Apparently Northwesterners are not afraid of heights and have a yen for adventure. We draw that conclusion because the industry of zip line tours and aerial adventure parks is booming in the Northwest right now.

Within the past couple years, fully a dozen commercial zip line attractions have opened in Oregon, Washington and Idaho… not counting at least twelve more in British Columbia and Alaska. The revenue potential has some municipal parks departments looking to add spendy zip line attractions in public parks.

I am flying from tree-to-tree up to 55 feet over the forest floor. I’m strapped in a harness under a pulley and I’m trying out the region’s newest zip line and aerial challenge course. It’s at Northwest Trek Wildlife Park near Eatonville, Washington.

17-year-old Cory Evan and his younger sister started talking about a return visit as soon as they finished their first time through.

“I’m really scared of heights, like I don’t do roller coasters because I’m scared of heights,” he says. “But I was able to do this, which is really big for me. It was a lot of fun.”

Tacoma, Washington’s public park district owns Northwest Trek. Business manager Donna Powell pitched the zip line construction to the board of commissioners.

“We needed something that was going to set us apart from the other experiences around here. We also wanted to attract a different demographic.”

Powell projected the zip line concession would boost attendance at the wildlife park by drawing in more teenagers, young adults, and people interested in more active pursuits.

“We could do a mountain beaver exhibit but I doubt that is going to increase our attendance by 5,000 people in a year.”

But with the zip line course, Powell says park attendance and revenue has surged just as hoped.

Things haven’t gone so well for some other aspiring zip line operators. A former Washougal, Washington entrepreneur spent five days in jail for operating a zip line course in the Columbia Gorge without first obtaining the proper permits. That man has since relocated his business to Maui.

This summer, intense community opposition derailed plans by a British company to string zip lines in a Seattle public park. Opponent Trileigh Tucker says the expensive attraction would’ve ruined a quiet retreat in the big city. The Seattle University professor says zip line expansion on public park land bears watching.

“In regard of commercial use of open public spaces, I think there is a precedent or a wider principal at play here: which is a sense of some kind of moral violation by privatization of public parks.”

Tucker quickly adds that she does think zip line development “can be done right” given the right setting.

More development is definitely on the way. Businessman Erik Marter estimates the number of zip line attractions in the Northwest states will double over the next year.

“I think we’re a little ways off a saturation point,” Marter says. “I think it’s going to be a while before we have so many of them out there.”

Marter co-owns a Portland-based company named Synergo. It designs and builds commercial zip tours among other things.

“I don’t think there is anyone pushing it,” he says. “I think people are hearing about it. We don’t do any marketing on it. People are calling us; we’re not calling out to set these up. A lot of people are interested. It doesn’t cost that much to make them, comparatively speaking to an amusement park or even a Ferris wheel or something like that… and they’re really fun.”

And safe, according to Marter. He says he knows of no serious injuries on commercial zip tours in the Northwest.

Description: Eight zip lines and a bridge between trees and over lakes and wetlands on 40 acres of forest on San Juan Island. 3 hour zip line course comprised of six main zip lines, plus two practice zip lines at the beginning. Like Canopy Tours NW, Zip San Juan’s course was built by Synergo.

Description: Bellevue’s parks department is collaborating with zip line course designer Synergo on an attraction to be built next year in Eastgate Park. The 24-acre park is already home to an existing ropes challenge course.